Remove the stems from each chili shaking out as many seeds as possible and place in a large bowl. Cover chilis with boiling water and top with an upside down plate to keep submerged. Let sit until softened, at least 30 minutes.
While chilis are softening, heat a deep pan over high heat and drizzle with canola oil. Sprinkle pork chunks with 2 teaspoons of the salt, pepper and 1 tablespoon of the oregano. Brown pork in a pan until pieces start to form a crust. This should take about 7-8 minutes.
Once the pork is seared, remove from pan and place in the slow cooker insert.
Add chicken broth, hominy and remaining 1 tablespoon oregano to the slow cooker.
To make the red chili paste, place softened chilis and 1 1/2 cups of the soaking liquid into a blender or food processor. Add onion, garlic and remaining 1 teaspoon salt then puree until smooth.
Place a fine mesh strainer over a large bowl and pour chili paste over the strainer. Use a spatula to push the chili paste through removing any large pieces. Taste paste for seasoning and add salt or pepper if needed.
Pour chili paste into the slow cooker and stir well. Heat on low for 8 hours or high for 4 hours.
Add lime juice to the posole before serving, being sure to add salt or pepper if necessary. Serve stew in bowls with optional garnishes.